Resin-cloth structural and repair systems according to Pat. No. 4,519,856 have been used successfully in a wide variety of applications. With experience, and attempts to apply these systems more aggressively, it has been found, especially in applications where fluids under elevated pressures are to be contained, as in fire-fighting and damage-control systems aboard ships, and in hydraulic lines and lube oil lines, as some examples, that additional provision for preventing leaks of fluid through the repair is required. In presently-used systems it is desired that the cloth component of a repair system be soft and flexible, so that it can easily be shaped to conform with or wrap around a surface that is being patched or covered. Thus, while a cloth can be woven more densely to patch a roof or to seal a leak in a domestic water pipe, high pressures such as may be encountered in industrial fluid conduits, or aboard a Naval ship, require stronger and tighter repair systems that have up to now been available. However, simply adding strength to the yarns of which a cloth is woven is not a satisfactory solution to this problem, for the resulting cloth may fail to be adequately fluid-tight, or it may be too stiff and inflexible to be shaped or molded to a pipe or to a curved surface of a tank, for example, while the resin impregnating the cloth is becoming hard, or the resin may not be retained in the cloth well enough to prevent leaking of fluid that is under elevated pressure. The need is to construct a cloth which provides the necessary strength and leak prevention without being so hard and stiff that its usefulness is limited. This invention addresses that need.